Death of a sibling is a double loss for surviving siblings - loss of a playmate, confidante, friend, role model - and loss of parents whose grief leaves them with little to no emotional energy to reach out to their hurting surviving children. Approximately 2 million US children experience this each year, leaving 25% of them in need of clinical intervention and more than 50% with significant behavior problems. Many children respond to a sibling's death with anger, aggression, guilt, depression, suicidal thoughts and attempts, anxiety, poor school performance distance from parents, and confusion. Research in this area has changed from a focus on having children get over the sibling's death to calls for a more comprehensive approach to children's responses to sibling death within a family context. Current studies on responses of surviving siblings suffer from small and frequently biased samples, little to no minority or lower socioeconomic representation, and inclusion of newborn to adult sibling deaths in the same sample often conducted many years after the sibling's death. The purpose of this longitudinal, mixed methods study is to examine children's mental health, physical health, personal growth, and functioning from 2 to 13 months after death of a sibling in the PICU/NICU and identify factors related to these outcomes in White non-Hispanic, Black non-Hispanic, & Hispanic/Latino children. The proposed study's theoretical model posits that characteristics of the situation surrounding the death, characteristics of the surviving sibling, parent and family characteristics, and supportive resources affect surviving sibling grief. Sibling grief and supportive resources are posited to affect surviving children's mental health, physical health, personal growth, and functioning (aggressive behavior and school performance). Surviving siblings between 6 and 18 years old living with the deceased sibling's parent(s) will be included if they are in their age- appropriate grade in school + 1 year. Quantitative data will be obtained from both parents and children. Qualitative interviews with each surviving sibling will focus on the time around the deceased sibling's death, their thoughts and feelings about the death and life since the death, roles and relationships within their family since the death, and relationships/activities with friends and teachers/child care providers. Study findings will provide much needed information on factors that influence outcomes for surviving siblings. Study data will provide a much more comprehensive examination of sibling loss in the context of the family, so timely, culturally appropriate and effective interventions can be developed to promote health of both the surviving siblings and the family.